Influence of temperature, residence time, and solvent/feedstock mass ratio on overall product distribution and oil products quality in ethanol liquefaction of 230 polypropylene impact copolymer

Abstract

This work examined liquefaction of polypropylene into liquid products in the presence of ethanol with particular attention to the effect of temperature (325–400 °C), residence time (1–6 h) and solvent/feedstock mass ratio (1/1–4/1) on the overall product distribution, and composition of the oil products. The oil products obtained under the optimal reaction condition contained mainly alkanes, alkenes, alcohols and aromatics, which accounted for 42.41%, 22.81%, 3.51%, 1.05%, respectively. Increasing temperature and retention time enhanced aromatization reaction leading to increased yields of aromatic hydrocarbons. The higher heating value of the oil product was 45.72 MJ/Kg, which is comparable to the higher heating value (HHV) of gasoline. Volatility analysis shows that 50–85 wt% of the oil composition had similar boiling point range as gasoline (35−185 °C). These characterization results suggest that the oil could be used as a raw material for gasoline blendstock or chemicals. The interaction of three reaction parameters on the oil formation was further evaluated by the response surface method. Through the Box–Behnken design, the R2, F-value and p-value of analysis of variance were 0.9917, 93.20, and < 0.0001, respectively, showed that the model fitted well with actual experimental value. It is suggested that the reaction temperature affect the oil yield more significantly, compared to other two parameters. The response surface analysis showed that under the temperature of 376.7 °C, residence time 3.8 h and solvent/feedstock mass ratio of 1/1, oil yield of 98.32 wt% can be achieved without adding catalyst or hydrogen. This predication was also verified by experiment.